A practical reference on Carcinogenicity: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Safety concerns emerged from long-term animal studies. In rodents given the compound for extended periods, researchers found an increased incidence of certain cancers, including liver and bladder tumors. These findings contributed to the discontinuation of clinical development. Whether similar risks apply to short-term or low-level exposure in humans is not established, and controlled human safety data are limited. The relevance of high-dose rodent carcinogenicity findings to human use remains a subject of debate.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
GW501516 acts as a selective agonist at PPARδ, a nuclear receptor that regulates transcription of genes involved in lipid handling and energy metabolism. Activation of PPARδ in preclinical models increases fatty acid oxidation, mitochondrial biogenesis, and exercise endurance in rodents. These effects have made the compound a subject of metabolic research and also a target for sport anti-doping rules. In humans, however, controlled studies are limited, and whether similar endurance or metabolic changes occur at tolerated exposures remains an open question. The receptor’s broad tissue distribution also means downstream effects may vary by organ and condition.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid metabolism |
| Preclinical effect | Increased fatty acid oxidation | Observed in rodent studies |
| Key safety signal | Tumors in rodents after long-term exposure | Contributed to halted clinical development |
| Human trial status | No approved product; development stopped | Limited short-term metabolic data |
| Sport regulatory status | Prohibited at all times | WADA hormone and metabolic modulators class |
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
GW501516 acts as an agonist at the peroxisome proliferator-activated receptor delta, a nuclear receptor that regulates gene expression. Activation shifts transcription toward genes involved in fatty acid uptake, oxidation, and energy expenditure. The compound does not bind the androgen receptor and therefore differs from anabolic steroids and SARMs. In rodent models, this metabolic shift has been linked to increased running endurance and reduced fat accumulation. The exact downstream pathways in humans remain incompletely characterized.
Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.
Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
== Mechanism of action == Copanlisib is an inhibitor of phosphatidylinositol-3-kinase (PI3K) with inhibitory activity predominantly against PI3K-α and PI3K-δ isoforms expressed in malignant B-cells. It has been shown to induce tumor cell death by apoptosis and inhibition of proliferation of primary malignant B cell lines.
Isobutyryl-CoA + 6 malonyl-CoA +12 NADPH + 12H+ → Isopalmitic acid + 6 CO2 12 NADP + 5 H2O + 7 CoA The difference between (straight-chain) fatty acid synthase and branch-chain fatty acid synthase is substrate specificity of the enzyme that catalyzes the reaction of acyl-CoA to acyl-ACP.
=== Marketing === Il-86 provision to Aeroflot did not constitute a sale: it was part of the centralised Soviet supply and allocation system coordinated by offices called Gosplan and Gossnab which controlled the entirety of planning and distribution in the USSR (except the black market). Built aircraft were allocated to Aeroflot regions and Soviet Air Force units as follows (in order of first acceptance): the Vnukovo Aviation Enterprise, 21 aircraft; the TsUMVS Administration of International Air Communications centred on Sheremetyevo Airport, 22; the Tashkent Air Enterprise, 9; the Sheremetyevo Air Enterprise, 10; the Pulkovo Air Enterprise, 8; the Alma-Ata Air Enterprise, 8; the Chkalovsky Soviet Air Force Base 8 ADON (or 8th Special Purposes Aviation Division), 4; the Kol'tsovo Air Enterprise, 6; the Tolmachevo Air Enterprise, 6; the Erevan Air Enterprise, 2; the Yemelyanovo Air Enterprise, 3. Selling the Il-86 commercially (which under the Soviet system meant solely exports) was the job of the Soviet foreign trade organisation V/O Aviaeksport. The division of responsibilities between the influential TsAGI research establishment, design bureaux (acting like naval architects) which designed aeroplanes, factories (independent of the bureaux) which constructed them, independent service facilities which repaired them and an independent organisation which marketed them alongside designs by all other bureaux, has been seen as diluting responsibility for the fate of a product.
The three substrates of this enzyme are (R)-β-alanopine, oxidised nicotinamide adenine dinucleotide (NAD+), and water. Its products are β-alanine, reduced NADH, pyruvic acid and a proton. β-alanopine is a type of opine. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N-(D-1-carboxyethyl)-beta-alanine:NAD+ oxidoreductase (beta-alanine-forming).
NMR spectroscopy is one of the principal techniques used to obtain physical, chemical, electronic and structural information about molecules due to the chemical shift of the resonance frequencies of the nuclear spins in the sample. Peak splittings due to J- or dipolar couplings between nuclei are also useful. NMR spectroscopy can provide detailed and quantitative information on the functional groups, topology, dynamics and three-dimensional structure of molecules in solution and the solid state. Since the area under an NMR peak is usually proportional to the number of spins involved, peak integrals can be used to determine composition quantitatively. A common methodology involves an extended delay time between each spectral scan (generally, 5 times the longest T1 in a complex mixture for a 90 degree pulsing angle, where T1 can be calculated using techniques such as FLIPS). This lets nuclei relax completely, allowing integrals to be more accurate for quantitation. Structure and molecular dynamics can be studied (with or without "magic angle" spinning (MAS)) by NMR of quadrupolar nuclei (that is, with spin S > 1/2) even in the presence of magnetic "dipole-dipole" interaction broadening (or simply, dipolar broadening), which is always much smaller than the quadrupolar interaction strength because it is a magnetic vs. an electric interaction effect. Additional structural and chemical information may be obtained by performing double-quantum NMR experiments for pairs of spins or quadrupolar nuclei such as 2H.
Sources: en.wikipedia.org
Fatty acids with an odd number of carbons are found in the lipids of plants and some marine organisms. Many ruminant animals form a large amount of 3-carbon propionate during the fermentation of carbohydrates in the rumen. Long-chain fatty acids with an odd number of carbon atoms are found particularly in ruminant fat and milk. Chains with an odd-number of carbons are oxidized in the same manner as even-numbered chains, but the final products are propionyl-CoA and acetyl-CoA. Propionyl-CoA is first carboxylated using a bicarbonate ion into a D-stereoisomer of methylmalonyl-CoA. This reaction involves a biotin co-factor, ATP and the enzyme propionyl-CoA carboxylase. The bicarbonate ion's carbon is added to the middle carbon of propionyl-CoA, forming a D-methylmalonyl-CoA. However, the D-conformation is enzymatically converted into the L-conformation by methylmalonyl-CoA epimerase. It then undergoes intramolecular rearrangement, which is catalyzed by methylmalonyl-CoA mutase (requiring B12 as a coenzyme) to form succinyl-CoA. The succinyl-CoA formed then enters the citric acid cycle. However, whereas acetyl-CoA enters the citric acid cycle by condensing with an existing molecule of oxaloacetate, succinyl-CoA enters the cycle as a principal in its own right. Thus, the succinate just adds to the population of circulating molecules in the cycle and undergoes no net metabolization while in it.
The 8th district includes most of the northern and northwestern exurbs of Houston, including Conroe, part of Huntsville, Willis, Magnolia, Brookshire and Hempstead, along with parts of west Houston including Briar Forest, the western end of the Energy Corridor and most of the Bear Creek and Addicks areas in west Harris County. The incumbent is Republican Morgan Luttrell, who was elected with 68.2% of the vote in 2024. Luttrell is not seeking reelection in the heavily Republican district, which gave Donald Trump 63.2% and Ted Cruz 60.1% of the vote in 2024 and is a plurality White district with a 31.3% Hispanic voting age population.
=== Rupture === When Tarlov cysts are ruptured or drained they cause leakage of cerebrospinal fluid (CSF). Ruptures of Tarlov cysts have been reported associated with communicating aneurysms and from fracture in the proximity of the cysts. An undetected rupture can cause intracranial hypotension, including orthostatic neurological symptoms along with headache, nausea, and vomiting that improve when supine. The ruptured cysts can be patched either with a biosynthetic dural patch or using a blood patch to stem the flow of CSF.
==== Calcitonin gene-related peptide (CGRP) inhibitors ==== Atogepant (AGN-241689; Aquipta; MK-8031; Qulipta) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [131] Eptinezumab (ALD-403; Lu-AG09221; Vyepti) – monoclonal antibody against calcitonin gene-related peptide (CGRP) – migraine [132] Erenumab (Aimovig; AMG-334) – monoclonal antibody against calcitonin gene-related peptide receptor (CGRPR) – migraine [133] Fremanezumab (Ajovy; LBR-101; PF-04427429; PF-4427429; RN-307; TEV-48125) – monoclonal antibody against calcitonin gene-related peptide (CGRP) – migraine [134] Galcanezumab (Emgality; LY-2951742) – monoclonal antibody against calcitonin gene-related peptide (CGRP) – cluster headache, migraine [135] Rimegepant (BHV-3000; BMS-927711; Nurtec; Vydura) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [136] Ubrogepant (MK-1602; Ubrelvy) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [137] Zavegepant (BHV-3500; BMS-742413; PF-07930207; Vazegepant; Zavzpret) – calcitonin gene-related peptide receptor (CGRPR) antagonist – migraine [138]
=== Origin === Non-carbon-fixing proteins similar to RuBisCO, termed RuBisCO-like proteins (RLPs), are also found in the wild in organisms as common as Bacillus subtilis. This bacterium has a rbcL-like protein with a 2,3-diketo-5-methylthiopentyl-1-phosphate enolase function, part of the methionine salvage pathway. Later identifications found functionally divergent examples dispersed all over bacteria and archaea, as well as transitionary enzymes performing both RLP-type enolase and RuBisCO functions. It is now believed that the current RuBisCO evolved from a dimeric RLP ancestor, acquiring its carboxylase function first before further oligomerizing and then recruiting the small subunit to form the familiar modern enzyme. The small subunit probably first evolved in anaerobic and thermophilic organisms, where it enabled RuBisCO to catalyze its reaction at higher temperatures. In addition to its effect on stabilizing catalysis, it enabled the evolution of higher specificities for CO2 over O2 by modulating the effect that substitutions within RuBisCO have on enzymatic function. Substitutions that do not have an effect without the small subunit suddenly become beneficial when it is bound. Furthermore, the small subunit enabled the accumulation of substitutions that are only tolerated in its presence. Accumulation of such substitutions leads to a strict dependence on the small subunit, which is observed in extant Rubiscos that bind a small subunit.
Sources: en.wikipedia.org
Rodent studies reported increased endurance and fat oxidation after GW501516 exposure. Long-term studies also found higher rates of some tumors, which led to halted development.
Small short-term human trials examined metabolic markers such as lipids and glucose. The trials did not continue after rodent cancer findings, so long-term human safety is unknown.
Controlled human trials have not established a performance benefit. Anecdotal reports exist, but they are not reliable evidence.
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.